The present invention relates to a continuously variable traction roller transmission.
A conventional continuously variable traction roller transmission is shown, for example, in the Publication entitled "Machine Design", p. 155, published on Apr. 18, 1984. This transmission includes two continuously variable transmission units. The transmission units comprise two input traction discs, and two output traction discs which are coupled to each other for unitary rotation, respectively. Accordingly, with a shift control valve for one of the first and second transmission units, the two transmission units are controlled.
A problem encountered in such continuously variable traction roller transmission having two transmission units is such that, while the transmission unit is shifting under control of the shift control valve, a pair of roller support members of the other transmission unit are subject to vibration, increasing tendency to induce slippage. Specifically, even though vibration of a pair of roller support members of the transmission unit operated by the shift control valve is hydraulically attenuated, whereas vibration of the other pair of roller support members is not attenuated to a low level. This produces a variation in torque, creating a condition where slippage tends to occur.